1. Field
Example embodiments relate to a semiconductor device and methods of manufacturing the same. Other example embodiments relate to a ZnO based thin film transistor including an active layer using a composite semiconductor material in which a zinc (Zn) oxide is doped with gallium (Ga) and indium (In) and methods of manufacturing the same.
2. Description of the Related Art
Research on organic light-emitting diodes (OLED) having a relatively large area has been actively conducted. As a driving transistor for OLEDs, a transistor that stably operates with constant current characteristics and has improved durability needs to be developed. Amorphous silicon TFTs may be manufactured using a low temperature process, but such TFTs may have relatively low mobility and may not satisfy constant current bias conditions. On the other hand, polycrystalline silicon TFTs may have increased mobility and may satisfy constant current test conditions, but may not have uniform characteristics. Thus, polycrystalline silicon TFTs may not have relatively large areas and may require high temperature processes.
ZnO materials may have conductivity, semiconductivity, and resistance according to their oxygen content. A transistor including a ZnO based semiconductor material as an active layer has been reported. In order to apply the transistor including a ZnO based semiconductor material as an active layer to display devices including OLEDs and LCDs, stable driving characteristics, which present constant characteristics in an on or off state, may be required in addition to constant current characteristics.